This invention relates to an apparatus for cleaning a printing cylinder of a printing machine and, more particularly, to an improvement of a printing cylinder cleaning apparatus of a printing machine of a type that includes a cleaning brush for rotational contact with a blanket cylinder or the like to sweep up lint or other dust therefrom, and a scraper for removing such dust from the cleaning brush.
Printing cylinders in printing machines typically require periodic cleaning to remove ink sediment, lint or other dust therefrom. Among various types of such cleaning heretofore proposed, an apparatus uses a brush roll contained in a box-shaped casing having an aperture such that the brush roll supported for rotation is partly exposed beyond the aperture. The brush roll is rotated by a motor, and rotationally contacts a blanket cylinder beyond the aperture to scratch or scrape off lint or ink sediments from the surface of the cylinder. The casing also contains a scraper for biting engagement with the brush of the brush roll to remove dust therefrom.
In the existing cleaning apparatus of this type, the scraper is used to remove dust from the brush roll, and it is held in the casing such that it partly bites into the brush roll. The scraper has a rectangular cross section such that one of its edges enters into the brush roll to increase its dust removing effect. The scraper is also positionally related with the brush roll such that the tangential line passing their contact point extends to a dust collector located at the bottom of the casing to prevent scattering of dust removed from the brush roll by the scraper.
In operation of the existing cylinder cleaning apparatus, the scraper removes dust from the brush of the brush roll and makes it drop onto the dust collector at the bottom of the casing. Some of the dust, however, adheres to and remains on the scraper itself, and accumulates on the scraper after a long use of the apparatus. Such accumulated dust sometimes drops in a mass to the bottom of the casing, and may prevent smooth transportation of dust in the dust collector. The scraper therefore also needs its own periodic cleaning. Moreover, although the brush roll and the scraper are positionally related to direct the dust removed from the brush along the tangential line passing their contact point, accumulated dust on the fixed scraper may prevent such intended movements of the dust, and may even deviate it in all directions toward wall surfaces and other portions in the casing other than toward the dust collector. This inevitably promotes fouling of the casing interior.